Method of disposal of hot water soluble garments and like fabrics

ABSTRACT

A method of disposing of garments after use. The garments, linens, drapes, towels and other useful articles are provided as woven, non-woven, knitted or otherwise formed fabric of thermoplastic polyvinyl alcohol polymer fiber, the fiber being water soluble only at temperatures above approximately 37 DEG  C. and preferably above 50 DEG  C. After use, the fabric is subjected to water at a sufficient temperature to substantially dissolve the fabric whereupon the water and dissolved fabric are subjected to disposal.

RELATED APPLICATIONS

This is a divisional of application Ser. No. 08/299,760 filed Sep. 1,1994, which is a continuation-in-part of U.S. application Ser. No.07/881,685 filed May 12, 1992 now U.S. Pat. No. 5,207,837 which was acontinuation-in-part of U.S. application Ser. No. 683,290 filed Apr. 10,1991 now abandoned.

TECHNICAL FIELD OF THE INVENTION

The present invention involves a method of disposing of garments afteruse. Specifically, the garments are composed of non-woven, woven,knitted or otherwise formed film or fabric of thermoplastic polymer orfiber which are water soluble at temperatures only above approximatelynormal human body temperature (37° C.).

BACKGROUND OF THE INVENTION

Hospital patient care generates considerable quantities of infectiousmedical waste in primary and acute care facilities. There has been ageneral conversion from reusable, cleanable items, to disposable itemsover the last three decades. These conversions were made to promoteantiseptic techniques in patient care and to decrease the potential forcross-infections between patients, staff and the general public. Recentfederal and state government regulations such as the Medical WasteTracking Act of 1988 and OSHA Medical Facility rules have resulted in asubstantial increase in medical waste that must be classified as"infectious."

When a patient is admitted to a hospital, the patient producesapproximately 55 pounds of medical waste per day. Approximately 20% ofthis waste is infectious. The current stated objective of the AmericanHospital Association and the Centers for Disease Control is to treatmedical waste as soon as it is generated. Both organizations recognizethat medical waste is primarily an occupational hazard for health careworkers and not an environmental problem. The best way to deal withinfectious medical waste is to disinfect it at the point of generationand dispose of the treated medical waste with minimum handling andstorage on premises.

The need for an effective way to dispose of medical waste has beenhighlighted by the amendment made to 29 C.F.R. §1910.1030 which providesfor the federal regulation under the Occupational Safety And Health Act,29 U.S.C. 655, 657 to control bloodborne pathogens. Specifically, theAct calls for the establishment of an exposure control plan, thecontainment of specimens of blood or other potentially infectiousmaterials and the general tightening of precautionary measures tominimize the spread of disease. A safe and effective way to dispose ofhospital waste in the form of soiled garments and apparel would greatlyfacilitate compliance with the above-referenced Act.

As a result, consumption of medical disposable woven or non-wovenproducts has been growing at a rate of approximately 10% a year. In1988, sales totaled approximately 1.155 Billion Dollars. It is projectedthat by 1992, sales of medical disposable non-woven products will reach1.54 Billion Dollars.

Disposable medical fabrics are generally currently composed ofthermoplastic fibers such as polyethylene, polypropylene, polyesters,polyamides and acrylics. These fabrics can also include mixtures ofthermoset fibers such as polyamides, polyarimids and cellulosics. Theyare typically 10-100 grams per square yard in weight and can be woven,knitted or otherwise formed by methods well known to those in thetextile arts while the non-wovens can be thermobonded, hydroentangled,wet laid or needle punched and films can be formed by blow or castextrusion or by solution casting.

Although there is clearly a benefit in the use of disposables in themedical arts by avoiding the necessity of human contact with medicalwaste which is necessary in the cleaning of comparable reusables,non-biodegradable disposables are posing a problem which is only nowbeing recognized. Landfill sites are becoming increasingly burdened withdisposables which do not biodegrade for hundreds of years, if ever. Aslandfill sites become fully exploited, new sites must be found which arerightfully opposed by residents located proximate to proposed sitelocations.

It is clear that others have produced useful articles which at leastbreak down or are caused to change their physical confirmation whensubjected to hot aqueous solutions. For example, U.S. Pat. No. 3,314,809teaches the production of transparent flexible films from hydroxypropylcellulose which is taught to be "insoluble in water until the waterreaches a temperature of about 60° C." However, hydroxypropyl cellulose,unlike polyvinyl alcohol, does not solubilize in water but simply breaksdown forming a cellulose derivative residue.

The prior art has recognized uses for polyvinyl alcohol compositions inthe manufacture of water soluble useful articles. For example, U.S. Pat.No. 3,413,229 teaches the production of water soluble bags or pouchesfrom which packets or the like are produced containing such materials asdetergents, bleaches, insecticides, medicinals, chemicals, dyes,pigments, industrial additives and other materials. It is taught thatthe contents of the packets are dispersed merely by dropping the packetsinto water whereupon the bags dissolve and release their contents intoaqueous dispersions. However, the referenced patent teaches theproduction of such films which are both hot and cold water soluble.

Additional references, such as U.S. Pat. No. 3,859,125 teach theproduction of layered articles which include coatings of polyvinylalcohol. The subject reference teaches coating polyvinyl alcohol on apaper membrane whereby it is taught that the coated paper is soluble ineither high or low temperature water. Again, it is incorrect to believethat a cellulose sheet material would be "soluble" in an aqueoussolution. At best, cellulose merely disperses. Similarly, U.S. Pat. No.4,343,133 teaches the coating of polyvinyl alcohol onto a non-wovenfiber sheet impregnated with latices of polyvinyl acetate in themanufacture of a premoistened towelette which can be disposed of byflushing in plain water without danger of clogging a plumbing system.

There has been the teaching of various medical related products whichare generally in the form of articles coated with polyvinyl alcoholemployed to enhance disposal. For example, European Patent ApplicationNo. 87310534.0 (Publication No. 0272816) teaches the production of anostomy pouch which can be disposed of in a toilet bowel. The pouch isconstructed from laminants of water swellable cold water insoluble filmsand water-resistant tissue paper. Similarly, U.K. Patent Application No.2211088 teaches the production of a liner for a bed pan or urine bottlemade of polyvinyl alcohol. It is taught that the liner may be disposedof by treatment with water at a temperature above that which itdissolves.

Both U.K. Patent No. 1,187,690 and Japanese Patent No. 72041741 teachthe production of stand alone polyvinyl alcohol films which are watersoluble. The U.K. patent teaches the production of hospital bags andpacking material for such products as detergents and agriculturalchemicals while the Japanese patent teaches the use of polyvinyl alcoholfilms to make laundry bags which dissolve releasing soiled garmentscontained therein. However, neither reference teaches the unique filmsof the present invention which can be configured into useful garmentsand like materials and which are soluble in aqueous solutions only abovea threshold value.

It is thus an object of the present invention to provide a method ofdisposing of garments, linens, drapes, towels and other useful articlesafter use while avoiding additional burdens being placed upon landfilldisposal sites.

It is yet a further object of the present invention to provide a methodof disposing of garments, linens, drapes, towels and other usefularticles after use such that the garment can be solubilized and medicalwaste substantially sterilized in a single operation.

These and further objects will be more readily appreciated whileconsidering the following disclosure and appended claims.

SUMMARY OF THE INVENTION

The present invention involves a method of disposing of garments afteruse which comprises providing the garments as sheets or as woven,non-woven, knitted or otherwise formed fabric of thermoplastic polymeror fiber. The polymer or fabric garments are water soluble only attemperatures above approximately the normal body temperature (37° C.).The garments, linens, drapes, towels and other useful articles composedof said polymer formulation are subjected to water at a sufficienttemperature to substantially dissolve the garments whereupon the waterand dissolved polymer are subjected to disposal.

DETAILED DESCRIPTION OF THE INVENTION

The present invention deals with the disposal of film or fabricconfigured into such garments and articles as drapes, towels, covers,overwraps, gowns, head coverings, face masks, shoe coverings, CSR wraps,sponges, dressings, tapes, underpads, diapers, wash cloths, sheets,pillow covers, napkins and woven, non-woven, or otherwise formed fabric.Such products are generally employed in the medical industry both inhospitals, outpatient facilities and home environments.

Many of these products generally come into contact with human bodilyfluids and their disposal and disinfection has become a matter of majorconcern in light of the lack of biodegradability of prior products andthe potential spread of human fluid-born diseases such as hepatitis Band AIDS.

In order to cope with these difficulties, it is proposed that polymer orfabric employed in the manufacture of such items be composed of polymerfilms and/or fibers which are soluble in hot aqueous baths, includingwater, either alone or with the addition of surfactants, salts andbleaches above 37° C. and preferably above 50° C. Such fibers or sheetswould be insoluble in cold to warm baths below 37° C., the averagetemperature of the human body. Ideally, the polymer or fabric would besoluble in baths only above 50° C., and, most preferably the polymer orfabric garments would be soluble only in aqueous media between 80° C. to90° C.

Garments which are soluble in aqueous media below 37° C. are useless asinadvertent secretion of bodily fluids such as blood and urine wouldcause the polymer to solubilize. Working with polymer which dissolvesonly at higher temperatures such as above 50° C. or, ideally between 80°C. and 90° C. would prevent inadvertent solubilization yet remain idealin practicing the present invention. It is contemplated that disposal ina hot water bath such as a washing machine at or near the boiling pointof water dedicated solely to solubilizing garments, linens, drapes,towels and other useful articles produced herein would also be aneffective disinfecting media. As such, two objectives would beaccomplished, namely, that the polymer or sheets would be disinfectedand would be solubilized for disposal through the sewer system. Not onlywould this lessen the burden now being imposed upon current landfillsites but liquid sewer disposal would prove a comparative low costtechnique in ridding the user of such used garments.

Polymer or sheet materials useful in practicing the present methodcomprise polyvinyl alcohol with or without acetyl groups, cross-linkedor uncross-linked. The garments are comprised of polyvinyl alcoholhomopolymer that has been highly crystallized by post drawing or heatannealing. Ideal for use in the present invention would be a highlycrystallized, at least approximately 98% saponified polyvinyl acetate.Commercially, polyvinyl alcohol sold under the trademark Vinex 1003™ and1002™ by Air Products could be used herein. Useful fibers are typically0.5 denier to 5.0 denier and are preferably from 1.0-2.0 denier and mostpreferably sized at 1.2-1.5 denier. A commercially available product foruse in the present invention is either type T-B (VEE 1290) or type T-5(VPB 101) which are each available from Kuralon as its PVA fiber. Thismaterial is sold in 44 mm lengths. The T-B product is sized at 1.2denier while the T-5 product is sold in 38 mm staple lengths of 1.5denier.

The fabric useful in practicing the present invention can be constructedby any well known technique for making woven, non-woven, knitted orotherwise formed fabric. Such non-woven techniques useful in practicingthe present invention include spun bonding, melt blowing or wet laying,hydroentangling with cold water and/or thermally bonding with 30-70% ofthe surface melted to form, for example, a diamond pattern. Whenproducts, such as diapers, are configured of sheets of suitablethermoplastic material, the sheets are approximately 1 to 6 mils inthickness and more preferably 1 to 3 mils in thickness and mostpreferably approximately 1.5 mils in thickness. Suitable non-wovenfabric or sheets are approximately from 15 g/yd² to 200 g/yd² in weightand more preferably from 20 g/yd² to 70 g/² and most preferably from 25g/yd² to 80 g/yd². Knitted or woven fabrics are approximately 50%heavier as needed for binding tapes, cuffs and related appendages.

As noted in U.K. Patent No. 1,187,690, it is desirable to maintain aminimum level of moisture content of polyvinyl alcohol pellets prior tomelt extrusion. The reference teaches that if moisture content of a filmcomposition exceeds two percent by weight, steam evolves during the meltextrusion leading to the formation of fine holes or cavities in thefilm.

However, while the present invention also contemplates drying to a levelof approximately 0.5% (wt.) water or less the polyvinyl alcohol pelletsbefore extrusion and, subsequent to the film formation, moisture isreintroduced back into the film to prevent brittleness and maintainusefulness. It is contemplated that the final PVA film have between 1.5to 15% (wt.), preferably 5 to 10% (wt.) and most preferablyapproximately 7.5% (wt.) moisture content.

In order to further enhance the usability of sheet material producedprincipally of polyvinyl alcohol, it is contemplated that ananti-blocking agent be employed to reduce hydrogen bonding betweenadjacent hydroxyl groups on separate sheets. Suitable anti-blockingagents are members selected from the group consisting of silicon dioxide(SiO₂ ) polymer, talc, calcium carbonate and fumed hydrophilic SiO₂.Such material should be employed between 0.1 to 5.0% (wt.) and mostpreferably between 2 to 3% (wt.) based upon the weight of the polyvinylalcohol.

As noted previously, polymer or sheet material useful in practicing thepresent invention is comprised of polyvinyl alcohol with or withoutacetyl groups, cross-linked or uncross-linked. It is proposed that thepolyvinyl alcohol be substantially fully hydrolyzed, that is, having 98%or greater hydrolyzed acetyl groups.

For the sake of adequate mechanical strength, polyvinyl alcohol-basedsheet material should have a degree of polymerization of at least 700and no greater than approximately 1500. Ideally, such materials shouldhave a degree of polymerization of approximately 900 and besubstantially crystallized.

It is also noted that in producing polyvinyl alcohol resins from thesaponification of polyvinyl acetate, impurities such as sodium acetateand sodium sulfate are found in the resin. To provide a suitable filmmaterial, such impurities must be kept below 1/2% (wt.) and preferablybelow 1/4% (wt.) of the polyvinyl alcohol resin. This can beaccomplished with a methanol water rinse or extraction.

To enhance the manufacture of suitable polyvinyl alcohol resin-basedfilm materials, suitable quantities of a plasticizer are necessary. Itis contemplated that up to 15% (wt.) of a suitable plasticizer such asglycerine or polyethylene glycol be employed to assist in providing asmooth melt extrusion from the polyvinyl alcohol-based pellets.

As examples the following fabric samples were manufactured onconventional thermal bonding equipment.

    ______________________________________                                        I.D.      TL-0079.0 79.1    79.2  080.0 0080.1                                ______________________________________                                        Fibre     Kuralon T-5 PVA (1.5 denier,                                                  38 mm staple length)                                                Pattern No.                                                                             2         2       2     1     1                                     Fabric Wt.                                                                              27        44      47    35    43                                    (gms/sq. yd)                                                                  Thickness (mil)                                                                         15        12      17    14    16                                    Tensiles-                                                                     (Grab-lbs)                                                                    Dry MD    8.3       11.7    16.6  13.8  16.1                                  Wet MD    3.2       4.8     4.6   3.1   6.0                                   Dry CD    2.0       2.3     4.3   3.8   5.2                                   Wet CD    1.0       1.5     1.7   1.3   2.3                                   Elongation (%)                                                                Dry MD    11        10      12    12    11                                    Dry CD    48        30      38    19    22                                    Mullen Burst                                                                  (psi)                                                                         Dry       11        15      19    13    16                                    Wet       10        14      19    13    15                                    Hanle-O-Meter                                                                           84        244     432   173   244                                   (gms)                                                                         Trap Tear-                                                                    MD        1.7       2.1     3.5   2.7   2.9                                   CD        0.4       0.4     0.8   0.6   0.7                                   ______________________________________                                    

It was found that the above-manufactured fabric displayed nearlyidentical physical properties similar to fabric manufactured frompolyester and polypropylene. However, the fabric manufactured above wasunaffected by cool or warm water (23°-37° C.) but when exposed to hotwater (80°-90° C.), Immediately dissolved.

It is oftentimes desirable that the film be colored with pigments ordyes such as azo or anthraquinone molecules. Useful dyes include acids,basics, disperse, reactives and vats. The pigments and dyes should beemployed in an amount between approximately 0.25 to 3.0% (wt.) basedupon the weight of the polymeric polyvinyl alcohol.

Surprisingly, it has been found that the incorporation of a waterrepellent within the polyvinyl alcohol film or fabric is quite a usefuladjunct to minimize surface attack by liquid moisture at a temperaturelower than that at which solubility occurs. It has been found that evenwith polyvinyl alcohol films and fabrics which become water soluble onlyat elevated temperatures, when exposed to water, the surface of suchmaterial tends to take on a slick "feel" and the use of water repellentstends to minimize this effect. Suitable repellents include fluorocarbonsoffered by the Minnesota Mining and Manufacturing Co. sold under itstrademarks FC 824 and 808. These materials are useful in the range ofbetween 0.1 to 2.0% (wt.) based upon the weight of the polyvinyl alcoholpolymer.

I claim:
 1. Useful articles characterized as being water soluble only attemperatures above 37° C., said useful articles comprised of polymericfilm or fabric of polyvinyl alcohol including polyvinyl alcohol fiber,said film, fabric or fiber being configured into one or more membersselected from the group consisting of drapes, towels, covers, overwraps,gowns, head covers, face masks, shoe coverings, CSR wraps, sponges,dressings, tapes, underpads, diapers, wash cloths, sheets, pillow coversand napkins, said polyvinyl alcohol polymer being produced by reducingits moisture content prior to melt extrusion and subsequent theretoincreasing its moisture content to a value between approximately 0.5 to15.0% (wt.), said polyvinyl alcohol having a degree of polymerizationbetween approximately 700 to 1500 being produced from crystalline atleast approximately 98% saponified polyvinyl acetate and containingbetween approximately 0.1 to 5.0% (wt.) of an anti-blocking agent. 2.The useful articles of claim 1 wherein said film, fabric or fibercomprises a polyvinyl alcohol homopolymer that has been highlycrystallized by postdrawing or by heat annealing.
 3. The useful articlesof claim 1 wherein said moisture content after melt extrusion isincreased to approximately 5 to 10% (wt.).
 4. The useful articles ofclaim 1 wherein said moisture content after melt extrusion is increasedto approximately 7.5% (wt.).
 5. The useful articles of claim 1 whereinsaid anti-blocking agent comprises a member selected from the groupconsisting of silicon dioxide polymer, talc, calcium carbonate and fumedhydrophilic silicon dioxide.
 6. The useful articles of claim 1 whereinsaid anti-blocking agent is contained in said polyvinyl alcohol in anamount between approximately 2 to 3% (wt.).
 7. The useful articles ofclaim 1 wherein said polyvinyl alcohol polymer has a degree ofpolymerization of approximately
 900. 8. The useful articles of claim 1wherein said polyvinyl alcohol polymer further contains up toapproximately 15% (wt.) of a plasticizer.
 9. The useful articles ofclaim 8 wherein said plasticizer comprises a member selected from thegroup consisting of glycerine and polyethylene glycol.
 10. The usefularticles of claim 1 wherein any contaminants contained within saidpolymer of polyvinyl alcohol are maintained below approximately 0.5%(wt.).
 11. The useful articles of claim 1 wherein said fabric is woven,non-woven or knitted of said thermoplastic polymer fiber.
 12. The usefularticles of claim 1 wherein said thermoplastic polymer is water solubleonly at temperatures above 50° C. and insoluble at temperatures below50° C.
 13. The useful articles of claim 1 wherein said thermoplasticpolymer is water soluble only at temperatures above 80° C.-90° C. 14.The useful articles of claim 1 wherein said fabric is composed of anon-woven thermoplastic polymer of polyvinyl alcohol having a weight ofapproximately 25-80 g/yd² .
 15. The useful articles of claim 1 whereinsaid fiber is approximately 0.5-5.0 denier in size.
 16. The usefularticles of claim 1 wherein said fiber is approximately 1.0-2.0 denierin size.
 17. The useful articles of claim 1 wherein said fiber is fromapproximately 1.2-1.5 denier in size.
 18. The useful articles of claim 1wherein said fabric is prepared from said fiber by spun bonding.
 19. Theuseful articles of claim 1 wherein said fabric is prepared from saidfiber by melt blowing.
 20. The useful articles of claim 1 wherein saidfabric is prepared by wet laying and hydroentangling said fiber.
 21. Theuseful articles of claim 1 wherein said fabric is prepared by thermallybonding said fiber.
 22. The useful articles of claim 21 wherein saidfabric is thermally bonded after hydroentanglement of said fiber. 23.The useful articles of claim 1 wherein approximately 30-70% of thefabric surface is melted by thermal bonding.
 24. The useful articles ofclaim 1 wherein said film of polyvinyl alcohol is made from a processselected from the group consisting of blow extrusion, cast extrusion andsolution casting.
 25. The useful articles of claim 1 wherein saidpolymeric film or fabric includes a coloring pigment or coloring dye.26. The useful articles of claim 25 wherein said coloring pigmentcomprises a member selected from the group consisting of an azo andanthraquinone molecule.
 27. The useful articles of claim 25 wherein saidcoloring pigment or coloring dye is contained with said polymeric filmor fabric in an amount between approximately 0.25 to 3.0% (wt.).
 28. Theuseful articles of claim 1 wherein said polymeric film or fabricincludes a water repellent agent.
 29. The useful articles of claim 28wherein said water repellent agent is contained within said polymericfilm or fabric in an amount between approximately 0.1 to 2.0% (wt.).